Former
"Jon & Kate Plus 8" star Jon Gosselin is reportedly writing a tell-all book about his now-sour relationship with ex-wife Kate Gosselin, the mother of his eight children.

Since the couple's divorce, Kate's been the one telling her story in the press (and vilifying Jon in the process) -- but apparently Jon wants to tell his side of the story. He tells
In Touch that he's already written a book "about my feelings and my marriage. Kate will flip."

Adds Jon, "No one really knows what happened" at the end of the couple's union. "I think people want to hear my story. At this point, I don't care about Kate's reaction."

He's said in
recent months that doing the show was a "mistake" and that he thinks his ex's exploitation of their children, a set of sextuplets and a pair of twins, "disgusting and awful."